Hey Lukasz,
On Monday 11 May 2020 at 12:19:01 (+0100), Lukasz Luba wrote:
<snip>
> @@ -27,12 +29,15 @@ struct em_perf_state {
> * em_perf_domain - Performance domain
> * @table: List of performance states, in ascending order
> * @nr_perf_states: Number of performance states
> - * @cpus: Cpumask covering the CPUs of the domain
> + * @cpus: Cpumask covering the CPUs of the domain. It's here
> + * for performance reasons to avoid potential cache
> + * misses during energy calculations in the scheduler
And because that saves a pointer, and simplifies allocating/freeing that
memory region :)
<snip>
> diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
> index 5b8a1566526a..9cc7f2973600 100644
> --- a/kernel/power/energy_model.c
> +++ b/kernel/power/energy_model.c
> @@ -2,8 +2,9 @@
> /*
> * Energy Model of CPUs
Should this comment change too?
<snip>
> -static void em_debug_create_pd(struct em_perf_domain *pd, int cpu)
> +static void em_debug_create_pd(struct device *dev)
> {
> struct dentry *d;
> - char name[8];
> int i;
>
> - snprintf(name, sizeof(name), "pd%d", cpu);
> -
> /* Create the directory of the performance domain */
> - d = debugfs_create_dir(name, rootdir);
> + d = debugfs_create_dir(dev_name(dev), rootdir);
So what will be the name for the perf domain of CPUs now? cpuX?
<snip>
> @@ -142,8 +149,8 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb,
> */
> opp_eff = freq / power;
> if (opp_eff >= prev_opp_eff)
> - pr_warn("pd%d: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",
> - cpu, i, i - 1);
> + dev_dbg(dev, "EM: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",
> + i, i - 1);
It feels like changing from warn to debug doesn't really belong to this
patch no?
<snip>
> @@ -216,47 +274,50 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
> */
> mutex_lock(&em_pd_mutex);
>
> - for_each_cpu(cpu, span) {
> - /* Make sure we don't register again an existing domain. */
> - if (READ_ONCE(per_cpu(em_data, cpu))) {
> - ret = -EEXIST;
> - goto unlock;
> - }
> + if (dev->em_pd) {
> + ret = -EEXIST;
> + goto unlock;
> + }
>
> - /*
> - * All CPUs of a domain must have the same micro-architecture
> - * since they all share the same table.
> - */
> - cap = arch_scale_cpu_capacity(cpu);
> - if (prev_cap && prev_cap != cap) {
> - pr_err("CPUs of %*pbl must have the same capacity\n",
> - cpumask_pr_args(span));
> + if (_is_cpu_device(dev)) {
Something like
if (!_is_cpu_device(dev))
goto device;
would limit the diff a bit, but that may just be personal taste.
But appart from these nits, the patch LGTM.
Thanks,
Quentin
